1. Field of the Invention
The present invention relates to an optical variable power module incorporated in an optical apparatus, such as an electrophotographic copier, and, more particularly, to an optical variable power module comprising a detachable chassis attached to a frame of the copier, and movable optical units slidably mounted on the chassis.
2. Description of the Related Art
An optical variable power system includes movable optical units (e.g. a movable lens unit, a movable mirror unit and so on) for varying a magnification of a focussing lens system included therein. The movable optical units must be assembled in a precise manner, which necessitates troublesome minute adjustments of the movable optical units. Accordingly, the optical variable power system is preassembled as a module, which is then incorporated in an optical apparatus, such as an electrophotographic copier. The assembly of the movable optical units and the troublesome adjustment thereof can only be carried out externally, as the internal space of the optical apparatus is extremely restricted.
Further, it is troublesome to properly assemble, for example, the movable mirror unit, having a relative complex structure, on the chassis in such a manner that a longitudinal axis of the movable mirror unit is precisely extended perpendicularly to an optical axis of the movable lens unit.